This book is a great introduction to both the R program for item response theory (IRT) analysis and IRT modeling itself for readers who want a firm grasp on both skills. This book is a helpful manual for understanding IRT concepts and background concisely and for easily learning the freely accessible R programs for doing IRT analyses. Reading this book is like catching two birds with one stone. This book is clearly written and amazingly easy to follow from installing the R program and executing the R command to interpreting the executed results. This book also provides practical advice, guidance, and specific details on utilizing the R program for practitioners, researchers, and graduate students in an introductory or an intermediate IRT course. The authors explain the essential background of various IRT models and the logic of each model in terms of practical applications. A major strength of the book is its consistent use of detailed examples to illustrate the concepts, the practical applications of IRT, and the thorough explanation of results for the executed examples. Another strong point is the general approachability and clarity of the text. Both practical users of IRT and beginners of the R program will benefit from this clear text and detailed examples. As a practitioner who frequently uses IRT but has little experience with R for IRT analysis, I strongly recommend this book as a learning tool for both IRT and R IRT programs.
Dr. Hyeonjoo Oh, Senior psychometrician, Educational Testing Service
Dr. Hyeonjoo Oh, Senior psychometrician, Educational Testing Service